1. Field of the Invention
This invention relates generally to fastening devices and, more particularly, to an encapsulated fastener of the type adapted to be pushed and retained in an aperture in a panel and, in turn, to receive a threaded element, such as a screw, for mounting another article to the panel.
2. Description of the Prior Art
Encapsulated fasteners of the type referred to above are typically fabricated as a one-piece plastic component including a relatively flat head portion and a smaller area, protruding shank portion which together define an elongated, screw or other threaded element receiving bore or space. The shank portion of the fastener is pushed into a panel aperture until the head portion contacts the panel surface. The article to be mounted to the panel, which may be a bracket, a second panel, or any other such article, is brought against the head portion of the fastener and is clamped thereto by tightening the screw into the bore of the fastener. Typically, the shank portion of the fastener is long enough to accept the fully tightened length of the screw so that the screw is concealed or encapsulated therein. Fasteners of this type are shown, for example, in U.S. Pat. Nos. 2,788,047; 3,404,596; 3,593,612; 3,703,120; 3,830,134; and 3,869,958.
Encapsulated fasteners have been used in a wide variety of applications. The fasteners have been particularly useful in the manufacture of refrigerator and freezer cabinets for mounting shelf supporting brackets and the like to the inside panels of the cabinets. These appliances generally have a double wall construction including an inside panel and an outside panel with the space between the panels being filled with an insulative foam.
In this, as in most other applications, it is important that the fastener be capable of firmly gripping the aperture defining edges of the panel and of retaining itself in the aperture in all instances against inadvertent or accidental removal. The fastener should also be capable of sealing the aperture to prevent the leakage of the insulative foam through the aperture and onto the exposed surface of the panel. Ideally, the fastener should exhibit these retention and sealing abilities even prior to the time that a screw is tightened therein. In the manufacture of refrigerator/freezer appliances, the fasteners are usually added to the various panel apertures, followed by the blowing-in of the insulative foam under pressure in an uncured or relatively liquid state and then by the curing or solidifying of the foam in position. The screws and shelf supporting brackets and the like are usually not added until after the foam has cured.
Prior encapsulated fasteners have been less than totally effective in the refrigerator/freezer application. Many prior fasteners are simply not designed to firmly grip the aperture defining edges of the panel until a screw is fully tightened therein. In other fasteners, the panel gripping members are too weak and flexible to hold the fastener in the aperture under the pressure of the added foam. In still other fasteners, the panel gripping members are not capable of taking up tolerances in the thickness of the panel and lose their effectiveness if the panel thickness is not just right. As a result, the fasteners often become totally or partially dislodged during the foaming process, causing the foam to leak through the aperture and to solidify on the exposed surface of the panel. Effort must then be expended in removing the leaked foam and properly inserting the dislodged fasteners, which effort adds to the overall cost of the appliances.
The fastener of the present invention is designed specifically to possess improved aperture retention and sealing abilities of the type required in refrigerator/freezer and related applications.